1. Field of the Invention
The present invention relates generally to a method and system for wireless communication, and, more particularly, to a method and system for peer-to-peer wireless communication over an unlicensed communication spectrum without routing or relaying of messages.
2. Description of the Related Art
Wireless communication is one of the most rapidly developing areas of communication today. A number of technologies and devices such as the cell phones, pagers, PDAs, CDMA, Wi-Fi, and Bluetooth, are on the market enabling people to communicate without being tied to wires bound to stationary locations.
Among the existing wireless communication methodologies, technologies such as the cell phones, CDMA, and Wi-Fi require extensive infrastructure. For these technologies, wireless communication is possible only within the effective areas of infrastructure availability. In addition, infrastructure-based wireless communication services typically require paid subscription with considerable fees so that the service providers may recover substantial investments made in laying down the extensive infrastructure. Thus, much of the existing infrastructure-based wireless communication services may be beyond the reach of many users due to geographic and economic constraints or limitations. It can be seen, then, there exists a need for a method and system for low-cost wireless communication that does not require extensive infrastructure.
A method of communication that does not require extensive infrastructure is peer-to-peer communication. Well-known in the art, peer-to-peer communication involves direct communication between devices without the need for intermediaries. In particular, peer-to-peer wireless communication utilizing unlicensed spectrum can provide a basis for low-cost wireless communication, since there is no need to pay for spectrum licenses, in addition to having no need to invest in extensive infrastructure to serve as communication intermediaries.
A well-known technology that employs peer-to-peer wireless communication over an unlicensed spectrum is Bluetooth technology. See, Bluetooth Specification, version 1.0B, available at http://www.bluetooth.com. However, an important limitation of Bluetooth technology is the range of communication, which is a distance of 10 to 100 meters. Bluetooth is mainly intended for device to device communications, e.g., between a computer and a peripheral device such as a printer or a keyboard, and, hence, the operational range of 10 to 100 meters is quite sufficient. Limiting the operating range also allows Bluetooth to avoid a host of problems that must be addressed by peer-to-peer wireless communication in a wider area.
There are two basic problems that peer-to-peer wireless communication operating in a wider area (e.g., an area within a range of a few miles) must resolve. One is the issue of power, and the other is communication traffic collision and congestion. The intensity of radio signal decreases by the square of the distance from the point of origin. Thus, the transmitted power of a signal must increase by the square of the distance of operation as the operating range of radio communication is extended. Hence, wireless communication that covers a wider area must address the need of generating power which grows as the square of the range of operation. In addition, the wider the operating range, the more devices are likely to be within the area of operation, trying to communicate with one another. Thus, the problem of communication traffic collision and congestion is much more likely to be severe.
Bluetooth avoids both of these issues by limiting its range of operation to about 10 meters. This limitation, however, makes Bluetooth essentially useless for most personal communications, since there is no need to resort to electronic devices for people to communicate with each other within 10 meters. People can just talk to each other.
Known in the art is a wireless, peer-to-peer, capability addressable network as disclosed in U.S. Pat. No. 6,069,896 (the '896 patent). The '896 patent, however, is directed to and limited to “capability addressable network”. In addition, the '896 patent discloses no collision avoidance mechanism. Thus, a wireless communication device in accordance with the '896 patent cannot provide effective communication when a multitude of devices are communicating within the same area at the same time. This means that the range of operation must be limited for the reasons discussed above. In reality, invention according to the teachings of the '896 patent cannot be effective beyond a few hundred meters. Furthermore, the '896 patent discloses no power conservation mechanism for peer-to-peer wireless communication. As discussed above, the power requirement and management problems are critical issues for medium to long range wireless communication.
Power management is particularly crucial issue for mobile or handheld wireless communication devices, since those devices typically operate on rechargeable or disposable batteries. A key issue in power management of mobile wireless communication devices is relaying or routing of messages. Most existing wireless communication technologies include methods or protocols for a device to relay or route messages which are destined to reach another device. In fact, for these technologies, much (often the majority) of the power consumption is due to relaying and routing activities. Hence, for mobile devices, it is an important question whether relaying and routing functions are worth the cost of the drain on precious battery power. Nevertheless, existing technologies, including the '896 patent and Mobile Ad hoc Networks (MANET) contemplate and rely on relaying and routing functions.
It can be seen, then, there exists a need in the field for a method and system for wireless peer-to-peer communication over an unlicensed wireless communication spectrum within a medium-range distance without routing or relaying of messages.